Known mobile speed estimation algorithms can be briefly grouped into two categories: time-domain approaches, e.g. based on the covariance approximations on the envelope level crossing rates (LCR) or average fade duration, and frequency-domain approaches based on the Doppler spectrum or on some parametric spectral analysis. Such methods for speed estimation include estimating the maximum Doppler frequency using spectrum methods, calculating the squared deviations of the logarithmically compressed received envelope, zero-crossing estimators, frequency domain time covariance analysis and wavelet-based approaches. These methods give generally good results at vehicular speeds (larger than 30 km/h). However, these algorithms are quite complicated and they do not work satisfactorily at very low speeds (e.g. pedestrians speeds up to 6 km/h).
JP 04-157388 A2 discloses a method and device for measuring at least one of acceleration, speed and moving distance of a moving body by determining a phase difference between standing waves of the same frequency which are received simultaneously by two antennas provided along the direction of movement of the moving body. A standing wave of a half wavelength formed in a space by an FM radio wave emitted from an FM station is received by the antennas. The rear antenna (in the direction of movement) receives the wave in a time delay compared to the front antenna. By correlative processing the time delay is calculated wherefrom the ground speed of the moving body is calculated.